3D morphometric study of domestic fowl glomerulus-A scanning electron microscope study of vascular corrosion casts.

Microvascularization of domestic fowl kidneys was studied using scanning electron microscopy (SEM) of vascular corrosion casts (VCCs). Two types of nephrons, mammalian-type (MT) and reptilian-type (RT) nephrons and their glomerular structure were analysed quantitatively by 3D morphometry. A significant difference in shape and size between the MT and RT glomeruli was found. The mean diameter of the RT glomeruli was about 56 µm, while that of MT glomeruli was significantly larger, namely about 80 µm. The afferent arterioles in mammalian-type glomeruli usually bifurcated into two lobular branches and formed a complex glomerular capillary network with numerous loops. Reptilian-type glomeruli consisted of a single capillary forming few loops and leaving the glomerulus as efferent arteriole. Diameters of afferent and efferent arteriolar replicas were similar in all three kidney divisions of MT and RT nephrons. The absence of the interconnecting branches between the MT nephron capillaries at the gross inspection suggests that the mammalian-type nephron glomeruli, although more complex than the reptilian type, are not equivalent to those in mammalian kidneys.